Engine starter drive



May 18, 1948. 1.. MILLER 1 2,441,772

ENGINE STARTER DRIVE '7 Filed Dec. 3, 1945 5 Sheets-Sheet 1 INVENTQR.

wlTNEss Q Q E 687569 "8'59 6.72.3277; W

A ORNEY y 1948. D. L. MILLER 2,441,772

ENGINE STARTER DRIVE Filed Dec. 5, 1945 s Sheets-Sheet 2 INVENTQR. v

A ORNEY Maly 18, 1948. D. L. MILLER 2,441,772

ENGINE STARTER DRI VE Filed Dec. 3, 1945 3 Sheets-Sheet 5 292a 13! 711 L, 1911121723 z 16 IN V EN TQR.

WITNESS MJLW. yan/214% Patented May 18, 1948 ENGINE STARTER DRIVE Donald L. Miller, Pine City, N. Y., assignor to Bendix Aviation Corporation, a corporation of Delaware Application December 3, 1945, Serial No. 632,526

, l The present invention relates to an engine starter drive and more particularly to that type of starter which remains in operative connection with the engine to be started until the operator acts to interrupt the starting operation. 'In this type of starter, the driving connection between the starting motor and the engine to be started may be continued by the operator until the engine is self-operative regardless of momentary or isolated impulses therefrom.

.It is an object of the present invention to provide a novel engine starter of the above type which is simple, reliable and of small dimensions.

It is a further object to provide such a device in which means under the control of the operator are used to initiate and continue the starting operation regardless of weak explosions and momentary impulses of the engine to be started.

It is a further object to provide such a device wherein a plunger member, which may be under the control of the operator, governs the disengaging movement of an engine driving memberduring the starting operation.

It is a further object to provide such a device in which a rotary member cooperates with a plunger member to hold the engine driving memment of the engine driving member away from the engine member until a reliable engine start is secured.

It is another object to provide such a device wherein the above mentioned plunger member is supported and connected so as to be freely slidable regardless of centrifugal forces acting thereon. 4 I

It is also an object. to provide such a device having an overrunningflclutch and means responsive to centrifugal force for fric'tionally augmenting the overrunning torque'of the clutch .in the driving connection for the' engine driving member whenever excessive rotational speedsare developed during the starting operation. I, A still further object is to provide'such a" de-- 15' Claims. 01. 74-7) vice in which a rotary lock for the above mentioned plunger member is provided with means for enabling said plunger to forcibly retract to idle position if the contact pressure between the position;

Fig. 2 is an end view of the device shown in Fig. 1 with the rotary lock in position to prevent drifting of the pinion away from idle position;

Fig. 3 is a view similar to Fig. 1 showing the starting drive in operative position;

Fig. 4 is a view partly in section of a modification of the mechanical detent shown in Fig. 3, illustrating a vacuum-operated detent for the rotary locking member; v

I Fig. 5 is a view similar to Fig. 1 showing the "starting drive partly demeshed in overrunning or locked position;

Fig. 6 is an end View from the left of Fig. 5;

Fig. 'I is a perspective view of the screw shaft, casing and control nut of the starting drive in disassembled relation and partly broken away;

Fig. 8 is a fragmentary detail view in side ele: vation, partly in section, of an embodiment of the present invention having a centrifugally released type of locking member;

Fig. 9 is a detail of arotary locking member having an alternative form of conical opening therein;

Fig- 10 is a side elevation partly in section of another embodiment of the present invention;

Fig. 11 is a view of the left end of the starting drive as shown in Fig. 10;

Fig. 12 is a perspective detail View of the rotary locking member and the cooperating plunger and screw shaft of Fig. 10, shown in disassembled rean anchor" pin 5 and lock' vvi're6.- Screw shaft 4 Fig. 1,

is provided at its forward end with threads 1 and at its rearend with a head portion 9 of enlarged diameter. A control member in the form of a nut 9, having a flange I i and a smooth cylindrical extension [2, is mounted by means of threads l3 on the screw shaft 4. An engine driving member in the form of a pinion It is slidably journalled-oILthc power shaft lfor trauersal.-.into..--

engagement; with an engine member suchas a gear l5 to crank the engine.

Means for actuating the pinion M by the con-.

trol member 9 are provided comprising a. resilient member in the form of a rubber sleeve IIia casing member l8 and a dentallclutch. comprisingns driving plate 23 and a drivenplatelzlra Sleeve. I1 is seated upon the control nut 9 and frictionally bears against the flange. H thereof. In.

order to hold the pinion Hi; clutch l9 and the rubber sleeve I1 assembled to the control. nut-1' 9, the casing member 18'. is formed as a barrel having a flange. 9. overreachingv the rear. side of. control nut flange. ii and. having. longitudinal slots ll, in.- the opposite end whichmeceivedlugs, 22. on the driving clutch plate 23.. The driven clutch plate 24, whichgisfixed to-the pinion 1 4.. by any.

suitable means suchas welding or brazing at 25, is held normally disengaged from plate 23 by a ,disc pring 29. positioned between the. plates,

and the separation. is limited by a clutch; housing ring 2.! which is. fixed in the end of casing; 18 in a suitable manner as by spinning; over the end 'of the. casing. so. as to/lockclutch plate 2i3iin said casing. A -thimbl'e 2.0, anchored. to thecasing I8 and slidably fitting the nut 9, is prefer.-

ably provided. to. enclose. therubber block I] and assist inthe frictional.transmission. of. torquefrom: said block to; the clutch. plate 23.

According to: the present -inyention,,means. are provided for maintaining the,- engagement ofv thepinion; M with the: engine gear.v while the. starter is energized, regardless. of. ncn continuous. ext.

plosionsr and impulses. of. the. engine. For. this purpose, the flange l9 of thebarrel Iiiisrecessed on. the; inner side-thereof to. forms a, clearance space: 2.8 and an. extendedr 'narrowed lip. 29,. and.

an axialy movableplunger or rod" 3-], is slidably mounted in anropening. 92 inthe. head 9.01; screw shaft 4 and. provided with a. groove. 3.3. forming a swivel connection; with. the, lip 29.. of casing. 19 whereby axialmovements. of the. pinion and; case mg; assembly are. transmitted. to. the; plung r. 31.

or detent thimblefl. mounted. on the screw: shaft.

head 8'with freedom for, limited rotation and adapted to cover the.- opening, al thereinn An opening 36: of; substantially greater diameter than.

all;

the-plunger: 3!. is. providedin the thim ble 34.1170. 1

allow the rear end of the plunger tow project. through the; thimblewhen. thethimble is rotated to bring opening 39 into aiign-menirwithopening 32.; Thimble 34,- is normally maint ined. inpcsition to: substant ally cover-the. 9 21 5 by a rs rr prizne 4:0. anchored; at; itsends to'the r w shaft. and thimbler 1 V a Means. are provided for enabling. the. rililr g 3$ to rotatathe locking :thirnble-fsl and. push its wayout throu h the p ning.- 36. when the. de=

. meshing fiO1TQ ;0H; the -plunger exceeds. adefinite.

value. As here shown, this is accomplished by forming a conical bevel or countersink 39 on the inner side of the opening 36 in the locking disc.

Means .for attaching the thimble to the screw shaft head 8 and limiting its rotation thereon are provided in the form of studs M seated in said head and extending through arcuate slots 42 in the; thimhlci. For the purpose I oireducing the frictional contact between; the, screw; shaft head and thimble to a minimum, circumferential "r dges 43 and 44 of semi-circular cross section are formed on the head 8 in an advantageous location'topromote free rotation of the locking mcmber:.- 1

The liocking; means 3|, is also arranged to operate as a -mcainst for preventing drifting of the pinion, I}! out of idle position. For this purand wearing properties. such. as cork. The start.-

ing, switch islocated in a. starting. circuit comprising. a battery 48.. grounded. at 5|, a lead as connectingthe battery tQ-the starting switch and a lead53 connecting theswitchto. the start- 7 ing. motor SMwhich is srounded'at. 54., A lead 55 connects thebattem 49 to a manual switch 59 which controls. the. energization of the starting switch coil .51.. the. circuit of which is completed.

through the. ground, at 58. r

In operation, closure of. the manual switch 555 permits current. from battery 49 to flow. through the, lead 95, switch 5.6. and switch coil 5]. to. ground at 58, thus. energizing coil. 51, andc'losing starting. switch -48. The'starting. circuit, is, thereby completed from battery 491 through, lead 52., Starting.

switch 48. lead.v 53. to. starting motor SM, and around. 5.4. Since the frictional. drag. member 46 is, mounted. on. the switch. armature 4.1, it is, raised out of contact with the rotating lock memberfi i.

by the closure of the, starting. switch. Rotation of power shaft. iand screw shaft 4. by the starting motor causes. control nut 9 and its associated parts. to. advance along the. screw shaft, pushing. the pinion M into mesh with the engine gear l5. and against, the stop shoulder 3. When the forward motion. of the pinion i4 is arrested by the. shoulder 9,. subsequent rotation of the. screw shaft. 4. closes. the clutch23. 2.4. against the pressure ofthespring 26. and compresses, the resilient sleeve I! which thus completes a yielding driving connection.

When the engine becomes reliably self-operative, the operator opens, the, manual switch 56 whichin turn. opens the starting. switch 43. The frictional drag member dothereupon descends and bears on the, thimblef 34,, causing it to be retarded with respect to the screw shaft 4 seas. to, bring the opening 39. thereof into, registry with he plun er 31 and. thus. free. the. plunger for backwar movement, thereby, per t ing. he pinion. M; to. demesh. from, the engine gear due to. the. accelerationof thejcontrol nut by the torque transmitted. from the, pinion back through the ov runnine. clutch. 2.3., 24' y v rtue of. the

"spring 26.. Ifi'wilL beundlerstood'that the ex ZAQM torsion spring .40 against thestuds 4| in a position to Qbstruot the rearward movement of the p un e 31;.

If the. clutch It should fail to disengage for any reason suchas the presence of rust or foreign matter, it may be desirable to, demesh the pinion. from, the engine; gear even though the operator fails to open the starting switch. This is accomplished as shown bybevelling, the end of, the. plunger 3! and correspondingly flaring the opening 36 inv the lock member 36;. The end of theplunger 3i. is thus adapted tov engage the inclined surface 39 of the lock member as illustrated in Fig. 9, whereby an excess of longitudinal pressure on the plunger will force the lock member 34 to rotate far enough to free the plunger and permit demesh ofthe pinion. When the plunger reaches idle position, the lock mem-. ber isurged into the recess 31' adjacent the shoulder 38v so'as to prevent the pinion M from drifting out of idle position.

A second embodiment of the present invention is illustrated in Fig. 8 in which a centrifugal member in the form of a steel ball 59 is mounted in a radial opening 60 in the head 3 of screw shaft 4.- and pressed inwardly against the plunger 3! by a.- circular spring Bi to govern the reciproeating motion of the plunger. In this form of the invention, the ball 59' is arranged to engage in the groove 37 to resist the demeshing of the pinion. The plunger 3| is also provided with a second groove 65 adapted to register with the ball 59 when the parts are in idle position, whereby the ball serves asan anti-drift detent' for the drive. In order to demesh the pinion from the engine gear, it is necessary for the demeshing force on the plunger 3| to build up to a magnitude large enough to overcome the spring and force the ball up the inclined shoulder 38 of groove 31'. When the drive is rotating rapidly, however, the centrifugal force of the ball 59 and spring 61' tends to balance the inward pressure of the spring, whereby the pinion is allowed to freely demesh. If only spasmodic impulses are transmitted to the pinion M by the gear I5, as in a false start of the engine, the spring 6| exerts pressure on the detent 5.9 to prevent longitudinal movement of the plunger 3! and to keep the pinion in mesh with the engine gear l5.

A. further. modification of the present invention is illustrated in Fig. 4 in which a frictional drag member 68 is actuated by avacuum-powered device 59 to perform the function of the drag member 46 of Fig. 1. This device has a vacuumchamber H connected by a tube !2 to the intake manifold 73 of an engine not. further shown. A spring, 14 bearing against, a flexible diaphragm i5 normally holds the drag member out of contact with thimble 34. .When, the engine starts, the vacuum produced in the intake, manifold acts on the. diaphragm to. overcome the spring and. press the drag; member against the thimble, thus permitting the pinion to demesh. from the engine gear.

In Figs; to 13, there is illustrated: an em:

bodiment. of heinveh n in rporating a yi lding member on the rotatable lock member which permits retraction of the plunger 88 when the mesh ns. p es rethe eon is; ex ss ve. th form of the invention, a screw shaft 16 is provided having; a head portion 11 formed on its rear face with a recess 18 in which is seated a torsion spring 19 which is arranged to control a; rotatable; locking thimble 83. In order to attach the spring to they screw shaft and thimble, the ends of the springare bent outwardly, one and anchored in a hole 8| on the screw shaft, 16 and the; other endv in a hole 82 on the rotatable lochmember 83, so located as to place the spring under suitable stress. Lock member 83. is journalled at-84' on the head 1'! and is held thereon by a lock ring 85; seated in a recess 89, thus; confining the, spring 19. An elongated hole 87 is provided in the wall of the thimble. 83, and a plunger 88' which is slidably mounted in the head ll of the screw shaft and has a swivel connection with the barrel member i8 is arranged to project. through said opening when the parts are in idle position.

Means for yieldingly opposing projection of the plunger 88. through the opening 81 so as to hold the pinion in mesh with the engine gear is provided in the form of a curved flat spring 89 having one end anchored at 90 to the thimble B3 and extending at its other end partly over the member so as to project into slots 93 and 94' in the rear face of the screw shaft head IT. Slots 93 and 9d are suificiently wider than lugs 94- and 52 to permit rotational movement of the loci; member 83 from locked position to. unlocked position; that is, to allow spring 89 to be moved into and out of the path of the plunger 88. As shown in Figs. 10 and 13, speed responsive means are provided for making the clutch 23, 24 more ciiective at excessive overrunning speeds to transinittercue from te pinion it through the rubber f'lEEYG' it to. control nut 91 for the purpose of 1 lug 98 to said weight. a

In the operation of the structure here shown. energization of the starting motor (not illustrated) moves the pinion I4 into mesh with the engine gear 5 and cranks the engine as described: in the previous embodiment. If a false start occurs, the pinion. attempts to demesh, pushing the plunger 38; back until it bears against the flat spring 89 in which position the pinion id wiil still be partially meshed with the gear 1 fail to release for any reason, increased pressure" 7 will be transmitted from the barrel l8 to the plunger 88, which'then flexes the flat spring 89 backward and permits the pinion M to demesh.

Under certain circumstances, the unaided overrunning torque of the clutch 23, 24 may not be great enough to overcome the resistance of spring 89 and permit the pinion M to demesh from the engine gear 15. If this should occur, the pinion continues to rotate with the engine gear after the engine is started and consequently attains a very high speed. A large centrifugal force is thereby generated in the friction brake member 95 to press it heavily against the clutch disc 23 and increase the torque delivered through the clutch to a magnitude great enough to force the plunger 38 backward, thus deflecting the spring 89 and demeshing the pinion.

Although certain embodiments of the invention have been shown and described in detail, it will be understood that other embodiments are possible and that various changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

1. In an engine starter drive, a motor shaft, a screw shaft fixed thereon having a head portion, a control nut threaded on said screw shaft, a pinion slidably journalled on said motor shaft for meshing with and rotating a gear on the engine to be started, means for driving said pinion including a yieldable member and a clutch, a plunger member axially traversing the head of said screw shaft, means connecting the plunger to the pinion for longitudinal movement in unison while permitting rotation of the pinion relative to the plunger, and means including a rotatable lock member arranged to obstruct traversal of said plunger member in a direction to demesh the pinion.

2. In an engine starter drive, a motor shaft, a screw shaft fixed thereon having a head portion, a control nut threaded on said screw shaft, a pinion slidably journalled on said motor shaft for meshing with and rotating a gear on the engine to be started, means for driving said pinion including a yieldable member and a clutch, a plunger member axially traversing the head of said screw shaft, means connecting the plunger to the pinion for longitudinal movement in unison while permitting rotation of the pinion relative to the plunger, and means including a centrifugal member operable on said plunger member for opposing longitudinal movement of said plunger and pinion.

3. In an engine starter drive, a motor shaft, a screw shaft fixed thereon having a head portion, a control nut threaded on said screw shaft, a pinion slidably journalled on said motor shaft for meshing with and rotating a gear on the engine to be started, means for driving said pinion from said control nut including a yieldable member and a clutch, a plunger member axially traversing the head of said screw shaft, means connecting the plunger to the pinion for longitudinal movement in unison while permitting rotation of the pinion relative to the plunger, said plunger having a circumferential groove and detent means cooperating with said groove to retain said plunger member in idle position.

v4. An engine starter drive as set forth in claim 2, including further an annular elastic member surroundingsaid plunger and cooperating with the centrifugal member to oppose longitudinal movement of the plunger and pinion- 5. In an engine starter drive, a motor shaft, a screw shaft fixed thereon having a head portion, a control nut threaded on said screw shaft, a pinion slidably journalled on said motor shaft for meshing with and rotating a gear on the engine to be started, means for driving said pinion from said control nut including a yieldable member and a clutch, a plunger member axially traversing the head of said screw shaft, means connecting the plunger to the pinion for longitudina'l movement in unison while permitting rotation of the pinion relative to the plunger, a rotatable lock member surrounding said plunger member for opposing longitudinal movement thereof and means for rotating said'lock to unlocking position when the demeshing force on said plunger reaches a predetermined value.

6. An engine starter drive as set forth in claim 5 in which the rotatable lock for the plunger has an inclined surface cooperating with said plunger to rotate said lock to unlocking position when the retracting force on said plunger reaches a predetermined value.

7. In an engine starting mechanism, a starting circuit including a starting switch and a starting motor; an engine starter drive mounted on the motor shaft including a headed screw shaft fixed thereon, an engine driving member slidably journalled on said motor shaft for engaging and rotating an engine member, and means for driving said engine driving member from said screw shaft, a slidable rod in the head of said screw shaft having a connection at one end thereof to the engine driving member, a rotary lock for limiting the demeshing movement of said rod and engine driving member, said rotary lock being swiveled on said head for movement into and out of locking position, spring means urging the look into locking position, and means responsive to opening of said starting switch for rotating the lock out of its locking position.

8. In an engine starter drive, a motor shaft, a screw shaft fixed thereon having a head portion, a control nut threaded on said screw shaft, a pinion slidably journalled on said motor shaft for meshing with and rotating a gear on the engine to be started, means for driving said pinion from saidcontrol nut including a yieldable member and a clutch, a plunger member axially traversing the head of said screw shaft, means connecting the plunger to the pinion for longitudinal movement in unison while permitting rotation of the pinion relative to the plunger, a rotary detent for controlling longitudinal movements of said plunger, and means responsive to self-operation of the engine for moving the detent to free said plunger for backward movement.

9. In an'engine starter drive, a motor shaft, a screw shaft fixed thereon having a head portion, a reciprocating member extending through said head portion having a circumferential groove, a control nut threaded on said screw shaft; a pinion slidably journalled on said motor shaft for movement into and out of engagement with a gear on the engine to be started, a driving connection between said nut and pinion, a casing member connected for axial movement to said pinion and having an inwardly extend ing flange seatedwithin said groove on said re:

ciprocating member, and locking means for obstructingrearward movement of said reciprocating member sufficient to permit demeshing of said pinion.

10. In an engine starter mechanism, a startciprocating member slidably traversing the head 7 portion of said screw shaft and having a swivel connection to the flange of said casing, a springbiased rotary look member journalled on the head of said screw shaft and opposing longitudinal movement of said reciprocating member, means for restricting relative rotation between said lock member and head, and a frictional drag member movable into engagement with said lock member by opening said starting switch and operative to cause rotation of the lock member on the screw shaft into position to release the reciprocating member.

11. In an engine starter, a power shaft, a screw shaft fixed thereon, said shaft having a rearward portion of enlarged diameter, a control nut threaded on said shaft, a pinion slidably journalled on said power shaft for traversal into mesh with and rotation of an engine gear, a driving connection between said control nut and pinion including an enclosure member, an elastic member and a clutch, a reciprocating member axially traversing the enlarged portion of said screw shaft and having a thrust connection to said enclosure member, a rotatable lock member journalled on the enlarged portion of said screw shaft cooperating with the reciprocating member to hold said pinion in mesh with said engine gear, a spring ring for positioning said lock member on the screw shaft in lock ing position, and means including an elastic member on said lock member for engaging the reciprocating member to hold the pinion in mesh, but adapted to yield on overload to permit demeshing of said pinion while said lock member is in locked position.

12. In an engine starter, a power shaft, a screw shaft fixed thereon, said shaft having a rearward portion of enlarged diameter, a control nut threaded on said shaft, a pinion slidably journalled on said power shaft for traversal into mesh with and rotation of an engine gear, a driving connection between said control nut and pinion including a casing member, an elastic member and a clutch, a reciprocating member axially traversing the enlarged portion of said screw shaft and having a thrust connection to said casing member, and means for opposing retrograde motion of said reciprocating member while the starting drive is operating including a lock member rotatably mounted on the screw shaft having a flat spring mounted thereon with its free end in the path of travel of said plunger. 13. In an engine starter, a power shaft, a screw shaft fixed thereon, said shaft having a head portion, a control nut on said shaft, a pinion slidably journalled on said power shaft for traversal into mesh with and rotation of an engine gear, a driving connection between said control nut and pinion including a casing member, an elastic member and an overrunning clutch, a reciprocating member axially traversing said head portion and having a thrust connection to said casing member, a lock member journalled on said head portion for cooperating with the reciprocating member to hold said pinion in mesh with said engine gear, said head portion having transverse slots, and said lock member having lugs engageable therein for limiting relative rotation thereof.

14. An engine starter drive as set forth in claim 13 including further speed responsive means for supplementing the overrunning torque of said clutch when rotated at excessive speed.

15. An engine starter drive as set forth in claim '13 including further a centrifugal clutch member mounted on said pinion and effective above a predetermined speed of rotation to transmit torque from the pinion to said control nut.

DONALD L. MILLER.

REFERENCES CITED UNITED STATES PATENTS Name Date Buxton Sept. 3, 1946 Number 

